Multi-stage compressor having interstage lubricant injection via an injection rod

ABSTRACT

A compressor is disclosed which can include a first stage and a second stage. In one form the compressor includes contact cooled compressor stages. The compressor can include a rod useful to inject a lubricant for purposes of cooling/lubricating/sealing the rotating components of the compressor. In one form the rod is an elongate rod with openings which permit a lubricant such as oil to be injected. The injected oil can be atomized via the openings. The rod can be positioned in the interstage space between the first and second stages, and can include a variety of openings.

TECHNICAL FIELD

The present application generally relates to industrial air compressorsystems and more particularly, but not exclusively, to a compressorsystem having lubricant/coolant injection.

BACKGROUND

Screw compressor systems are configured to produce a pressurized fluidsuch as compressed air or the like. Some screw compressors include oilflooded contact cooling lubricant systems. The cooling and lubricatingeffectiveness of the oil injection systems for oil flooded compressorsis vital to the operation of the compressor. Some existing systems havevarious shortcomings relative to certain applications. Accordingly,there remains a need for further contributions in this area oftechnology.

SUMMARY

One embodiment of the present invention is a unique compressor systemwith an injection nozzle configured to deliver lubricant/coolant to aflow of compressed working fluid. Other embodiments include apparatuses,systems, devices, hardware, methods, and combinations for injectinglubricant/coolant into a compression chamber of a screw compressor.Further embodiments, forms, features, aspects, benefits, and advantagesof the present application shall become apparent from the descriptionand figures provided herewith.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts one embodiment of a compressor.

FIG. 2 depicts a view of a compressor having an oil rod.

FIG. 3 depicts another view of a compressor having an oil rod.

FIGS. 4-9 depict embodiments of an oil rod.

FIG. 10 depicts an embodiment of an oil rod.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

Industrial compressor systems are configured to provide large quantitiesof compressed fluids at a desired temperature, pressure and mass flowrate. Some compressor systems can utilize a lubricant/coolant in theprocess of compressing a working fluid. Such lubricant/coolant can takea variety of forms, such as but not limited to oil. The term“workingfluid” should be understood to include any suitable compressible fluidsuch as but not limited to air. It should be understood that when theterm “air” is used in the specification or claims that other workingfluids are included under a broad definition of compressible fluids.Also, when the term “oil” or “lubricant” or “lubricant/coolant” is usedin the instant application, it should be understood that any lubricationfluid whether carbon based, synthetic, or natural is contemplatedherein.

Compressor systems such as those including screw compressors can belubricated, sealed and cooled with lubricant that is injected into acompression chamber having meshed male and female screw rotors. Contactcooled rotary screw compressors can include injection of lubricant intothe compression chambers to lubricate the contacting rotor surfaces,seal the clearance regions between the rotors, and cool the workingfluid as it is compressed.

Referring now to FIG. 1 , an exemplary compressor system 10 is showntherein. The compressor system 10 includes a primary motive source 20such as an electric motor, an internal combustion engine or afluid-driven turbine and the like. The compressor system 10 can includea compressor 30 that may include multi-stage compression. The compressor30 can include screw rotors operable to compress a working fluid such asair and oil vapor or the like.

A structural base 12 is configured to support at least portions of thecompressor system 10 on a support surface 13 such as a floor or ground.Portions of the compressed working fluid discharged from the compressor30 can be transported through one or more conduits 40 to a sump orseparator tank 50 for separating fluid constituents such as air and oilor the like. One or more coolers 60 can be operably coupled with thesystem 10 for cooling working fluids to a desired temperature in someembodiments. The one or more coolers 60 can cool working fluids such ascompressed air or oil to a desired temperature. The compressor system 10can also include a controller 100 operable for controlling the primarymotive power source 20 and various valving and fluid control mechanisms(not shown) between the compressor 30 and intercoolers 60 such as a blowdown valve 90.

The separator tank 50 can include a lid 52 positioned proximate a topportion 53 thereof. A seal 54 can be positioned between the lid 52 andseparator tank 50 so as to provide a fluid-tight connection between thelid 52 and the separator tank 50. Various mechanical means such asthreaded fasteners (not shown) or the like can be utilized to secure thelid 52 to the separator tank 50. A blow down conduit 80 can extend fromthe separator tank 50 to the blow down valve 90. The blow down valve 90is operable for reducing pressure in the separator tank 50 when thecompressor 30 is unloaded and not supplying compressed air to an endload. An air supply conduit 82 can be operably coupled to the separatortank 50 so as to deliver compressed air to a separate holding tank (notshown) or to an end load for industrial uses as would be known to thoseskilled in the art. An oil supply conduit 70 can extend from theseparator tank 50 to the compressor 30 to supply oil that has beenseparated from the working fluid in the separator tank 50 to thecompressor 30. One or more filters 81 can be used in certain embodimentsto filter particles from the oil and/or separate contaminates such aswater or the like from working fluids in the compressor system 10.

Turning now to FIGS. 2-3 , one embodiment of the compressor 30 isillustrated in the form of a multi-stage screw compressor including afirst stage 102 and second stage 104. The two stage oil flooded rotaryscrew compressor 30 depicted in FIGS. 2-3 compress a working fluid suchas air in a two-step process in which the first stage 102 compresses theworking fluid to an intermediate pressure followed directly by thesecond stage 104 that compresses the working to the final desiredoperating pressure. The compression process uses lubricant/coolant suchas oil in the compression chambers of the two stages to lubricatecontacting rotor surfaces, seal clearance regions, and remove heat fromthe working fluid as it is compressed. Common methods of suchlubrication/cooling include injection of oil in the first stage as wellas injection of oil as a solid fluid stream from one or many orifices.

The present application introduces lubricant/coolant in an interstageregion between the first and second stages 102 and 104 through the useof a rod 106 (referred to herein as an “oil rod” for sake ofconvenience, without any limitation intended as to the type of lubricantused) which is inserted upstream of the second stage 104 rotors.Lubricant can also be introduced elsewhere in the compressor 30,including during the first stage 102 compression process. In one formthe oil is introduced in the interstage region via an injector such asthe oil rod 106 that is specifically designed to produce an atomized oilspray.

As shown in FIG. 2 , working fluid enters the first stage inlet 108,travels through the first stage compression chamber 110 and exits viathe first stage discharge 112 into the interstage 114 which is theregion in which the first stage discharge 112 merges with the secondstage inlet 116. From here the air travels through the second stagecompression chamber 118, and out the second stage discharge 120. In someembodiments, oil can be injected into the first stage compressionchamber 110 via internal bores that feed oil to a location between theends of the rotor pair. Though the rotors are depicted as residing in acommon housing, in some embodiments the rotors can be separated. In onenonlimiting example the rotors can be connected via a conduit, pipe, orother suitable device. Such passages will therefore be understood toinclude any suitable throughway such as, but not limited to, a passageinternal to a common housing, a passage within a conduit or pipe, etc.

The oil rod 106 can be positioned and/or oriented in any number ofmanners suitable for the injection of coolant/lubricant. For example,the oil rod 106 is shown in the interstage region 114 located beneath ashelf 122 in FIG. 2 , but any other location suitable for the injectionof coolant/lubricant is also contemplated herein. To set forth just afew non-limiting examples, the oil rod 106 can be located closer to thefirst stage discharge 112 than depicted, and alternatively and/oradditionally be shifted axially relative to its illustrated position.FIG. 3 depicts the oil rod 106 being installed in a roughly parallelposition to that of a plane in which the axes of rotation of the maleand female rotor reside of the second stage 104. Such orientation canalternatively and/or additionally be roughly parallel to the plane inwhich the axes of rotation of the male/female rotor reside of the firststage 106. In other embodiments the oil rod 106 can be oriented in thespace between the first stage rotors and the second stage rotors in anorientation that extends toward either of the first stage 102 and secondstage 104. Alternatively and/or additionally, the oil rod 106 can beoriented such that it extends toward either of the axial ends of eitherthe first stage 102 or the second stage 104. It is noted that theapplication does not limit the relative location, position, orientation,etc. of the rod to the male or female rotor. In FIG. 3 the rod 106 isdepicted above the female rotor but it could just as equally be placedover the center of the rotors or over the male rotor. The oil rod 106can also be parallel to the rotor axis of rotation. It will therefore beappreciated that any combination of the above is also contemplatedherein. In short, the oil rod 106 can be located in any number ofpositions and be placed in any number of orientations anywhere betweenthe rotors of the first stage 102 and the second stage 104.

The oil rod 106 can be secured in place using any number of techniques.In one embodiment the oil rod can include a threaded surface structuredto engage a complementary threaded bore in a structure such as, but notlimited to, a housing that enclosed one or more components of thecompressor 30. Assembly into the compressor housing is not to be limitedby the design discussed and could include, by non-limiting example, avariety of thread connection types, damping or retaining features fromadditional components, press fit, etc. Other approaches are thereforecontemplated herein.

Turning now to FIGS. 4-10 , the oil rod 106 can take on a number offorms suitable for injecting lubricant into the compressor 30. FIGS. 4and 5 depict an embodiment which includes several orifices or openings124 formed near an end of the oil rod 106 which permit oil flowingwithin an internal passage 126 of the oil rod to exit and be dischargedinto the passing compressed flow stream. The openings 124 can bedesigned to produce a variety of spray patterns and characteristics, andin one form are designed to atomize and/or mist the oil into theinterstage prior to introduction of the compressed working fluid intothe second stage 104. In some forms the droplet sizes of the atomizedspray can be uniform in size when provided via a spray outlet, or canvary. The spray outlets can vary to produce a varying range of dropletsizes.

The passage 126 can extend in any configuration and to any length of theoil rod 106. In the illustrated embodiment the passage 126 is depictedas a central bore, but other embodiments can include differentconfigurations such as different path shapes (e.g. non-linear), greaternumber of passages (e.g. two or more, branching, converging), etc.

The openings 124 can take on any variety of shapes, configurations,geometry, quantity, orientations, etc. In the embodiments contemplatedherein, the distribution of openings 124 in the oil rod 106 can producean even oil spray that coats the entire or substantially entire exposedrotor surface area of the rotors in the second stage 104. As illustratedin FIGS. 4-5 , the openings 124 can be grouped toward an end of the oilrod 106 and can generally be oriented in the same direction orthogonalto an axis 128. The axis can generally represent a direction along whichthe oil rod 106 extends, though in some forms the oil rod 106 may notextend symmetrically along the axis. In some forms the axis of extensioncan be a singular axis around which the oil rod 106 symmetricallyextends. In other forms the axis of extension of the rod 106 can be ageneral direction along which the oil rod can extend, whether suchextension is along a straight line.

The openings 124 in FIG. 5 are generally oriented orthogonal to the axis128, but other directions are also contemplated in other embodiments(some of which are described further below). The openings 124 can extendin rows along the length of the oil rod 106 as seen in FIG. 4 , butother patterns are also contemplated. In addition, some rows can includefewer or greater numbers of openings 124 than other rows. In some formsthe oil rod 106 can include one or more openings 124 formed in the endof the rod 106, which although illustrated as a flat surface can alsotake on different forms in other embodiments. The openings 124,furthermore, can include a cross sectional area that remains constantbetween the internal passage 126 and the external surface of the rod inany of the embodiments herein, but variations in cross-sectional areaare also contemplated. For example, the side wall(s) that form theopening 124 can be parallel in some forms, but can also be tapered (e.g.conical in shape).

The oil rod 106 can include a head 130 which can be structured to aid inthe insertion of the rod 106 into the compressor 30. Such a head can behex in shape such as might be engaged by a socket or wrench, but othershapes are also contemplated. The oil rod 106 can include a shoulder 132useful to form a seal and/or cooperate with other structure to form aseal such as to discourage pressurized working fluid from escaping thecompressor 30. An o-ring can be disposed between the shoulder 132 andfeature 133, which in some embodiments can be a threaded feature. Thehead 130 can also include provisions to permit coupling with a lubricantsupply line such as via feature 135. Such coupling can be via quickdisconnect, but other techniques of attaching a lubricant line to thehead 130 are also contemplated herein.

Turning now to FIGS. 6 and 7 , another embodiment of the oil rod 106 isdepicted which includes a combination of non-uniform orifice holes withvarying orientations relative the longitudinal axis of the oil rod 106which act to direct and distribute the injected oil to specific areas.Some embodiments can include either the non-uniformity or the varyingorientations, or both. As seen in FIGS. 6 and 7 , the openings 124 areconfined around only 180° of the oil rod body. In some forms theopenings 124 can be grouped together to span less than 180°, while inother forms the openings 124 can span greater than 180° but less than360°. The openings 124 can also be concentrated in two or moresubgroups. The openings 124 located nearest the end of the rod 106illustrated in FIG. 7 are oriented in a non-orthogonal direction to theaxis 128 of the oil rod 106. It is therefore contemplated that theopenings 124 having similar orientations can be grouped in proximity toone another, and the groupings that result can provide a distribution oftwo or more orientations along the length of the oil rod 106. Suchembodiments can alternatively and/or additionally be distributed aroundthe entirety of the periphery of the oil rod 124 as shown in FIGS. 4 and5 , or can be confined to one side or groupings as shown/discussed inFIGS. 6 and 7 above. Additionally, embodiments can include one or moreopening in the end of the oil rod 106 as discussed above.

Still yet another embodiment is depicted in FIGS. 8 and 9 in which theopenings 126 are depicted as slots. The slots can run parallel to thelongitudinal axis of the oil rod 106. The openings 126 in FIGS. 8 and 9can include any of the variations discussed above for the otherembodiments including size, groupings, locations, orientation, shapes,configurations, geometry, quantity, cross sectional shape, etc. Theopenings 126 depicted in FIGS. 8 and 9 can produce a variety of spraypatterns as discussed above with regard to the other embodiments.

The embodiments of the oil rod 106 disclosed herein can be made usingany variety of techniques. For example, the oil rod 106 can be a singlepiece that is machined on a lathe or screw type machine from round orhex bar stock. In other forms the oil rod can be made from multiplepieces that are either welded or joined together via other techniques,some forms of which could include the use of perforated tube. FIG. 10depicts one form of a perforated tube. Such a perforated tube can bemade from a perforated sheet that is rolled and affixed to itself.

In some forms the system 10 can supply oil to the oil rod 106 at avariety of pressures, temperatures, and flow rates. Suchpressures/temperatures/flow rates/etc. can be regulated to varydepending on an operating condition of the compressor. Alternativelyand/or additionally, the oil rod 106 can include variable openings wherethe opening size and/or direction can be changed. These openings can bevaried during operation of the compressor and/or during an installationprocess which permits setting a value for such possible variations.

One aspect of the present application includes an apparatus comprising amulti-stage contact cooled compressor having a first stage rotarycompressor located upstream from a second stage rotary compressor, themulti-stage contact cooled compressor also including: a transfer volumelocated intermediate the first stage rotary compressor and second stagerotary compressor which is used to receive outflow from the first stagerotary compressor and convey the outflow to the second stage rotarycompressor, and an oil feed rod oriented to protrude into the transfervolume between the first stage rotary compressor and second stage rotarycompressor such that an exterior periphery of the oil feed rod isexposed to the outflow from the first stage rotary compressor, the oilfeed rod having an open interior for the receipt of oil as well as aplurality of openings formed in the exterior periphery of the oil feedrod through which oil from the open interior of the oil feed rod canpass into the transfer volume.

A feature of the present application includes wherein the oil feed rodextends from a wall that defines the transfer volume and terminates atan end, the exterior periphery of the oil feed rod defined between thewall and the end.

Another feature of the present application includes wherein the oil feedrod includes a circular cross sectional shape, and wherein each of theplurality of openings are symmetric.

Yet another feature of the present application includes wherein the oilfeed rod is in the form of a hollow tube, and wherein the plurality ofopenings are sized to produce a spray of oil droplets.

Still another feature of the present application includes wherein theoil feed rod protrudes along a centerline axis into the transfer volume,and wherein the plurality of openings each extend along an axis orientedat angle to the centerline axis.

Yet still another feature of the present application includes whereinthe oil feed rod includes at least one opening at the end of the tube.

Still yet another feature of the present application includes whereinthe openings of the oil feed rod include a plurality of elongated slotsthat extend along an elongate axis.

A further feature of the present application includes wherein the oilfeed rod includes an asymmetric distribution of the plurality ofopenings such that the plurality of openings are isolated on a portionof the exterior periphery.

Another aspect of the present application includes an apparatuscomprising; a first contact cooled compressor stage that includes afirst pair of compressor rotors, a second contact cooled compressorstage having a second pair of compressor rotors, a passage that connectsan outlet of the first contact cooled compressor stage to an inlet ofthe second contact cooled compressor stage, and an oil delivery rodhaving an external oil delivery surface positioned to extend into theinternal passage and structured to provide oil to a passing flow ofworking fluid produced by the first contact cooled compressor stage, theexternal oil delivery surface including a plurality of openingspositioned between a first exposed end of the oil delivery rod and asecond exposed end of the oil delivery rod.

A feature of the present application includes wherein the plurality ofopenings extend between an inner surface of the oil delivery rod and theexternal oil delivery surface.

Another feature of the present application includes wherein theplurality of openings have sidewalls between the inner surface and theexternal oil delivery surface, the openings extending at an anglerelative to an axis of extension of the oil delivery rod such that theangle is non-orthogonal.

Yet another feature of the present application includes wherein theplurality of openings are elongate slotted openings.

Still another feature of the present application includes wherein theplurality of openings are sized to atomize oil that is conveyed throughthe openings.

Yet still another feature of the present application includes wherein aspray pattern formed by the plurality of openings extends around theentirety of the periphery of the oil delivery rod.

Still yet another feature of the present application includes whereinthe plurality of openings includes an opening formed at an end of theoil delivery rod, and wherein at least some of the plurality of openingsare variable.

A further feature of the present application includes wherein the oildelivery rod includes a threaded surface structured to be threadinglyengaged with a complementary threaded surface structured to secure theoil delivery rod relative to the internal passage.

Yet another aspect of the present application includes a methodcomprising; compressing a working fluid with a multi-stage contactcooled compressor, routing the compressed working fluid from a firststage to a second stage of the multi-stage contact cooled compressor,and spraying oil out of an elongated oil rod in an interstage regionbetween the first stage and the second stage, the elongated oil rodhaving a plurality of openings arranged along a length of the elongatedoil rod such that oil is provided to the compressed working fluid fromthe first stage prior to being entrained in a compression process of thesecond stage.

A feature of the present application includes wherein the sprayingincludes atomizing the oil.

Another feature of the present application includes wherein sprayingincludes conveying the oil through the plurality of openings having aslot shape.

Still another feature of the present application includes wherein thespraying includes isolating the spraying to one side of the oil rod suchthat an oil spray pattern is not omni-directional.

Yet still another feature of the present application further includesspraying oil through an opening formed in an end of the elongated oilrod such that a spray pattern provided by the opening formed in the endof the elongated oil rod extends in a direction along a length of theelongated oil rod.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinventions are desired to be protected. It should be understood thatwhile the use of words such as preferable, preferably, preferred or morepreferred utilized in the description above indicate that the feature sodescribed may be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, the scope being defined by the claims that follow. Inreading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary. Unless specified or limitedotherwise, the terms “mounted,” “connected,” “supported,” and “coupled”and variations thereof are used broadly and encompass both direct andindirect mountings, connections, supports, and couplings. Further,“connected” and “coupled” are not restricted to physical or mechanicalconnections or couplings.

What is claimed is:
 1. A multi-stage contact cooled compressor having afirst stage rotary compressor located upstream from a second stagerotary compressor, the multi-stage contact cooled compressor comprising:a transfer volume located intermediate to the first stage rotarycompressor and the second stage rotary compressor, wherein the transfervolume is used to receive outflow from the first stage rotary compressorand convey the outflow to the second stage rotary compressor; and an oilfeed rod having an exterior periphery that extends in a longitudinaldirection, the oil feed rod oriented to protrude into the transfervolume such that the longitudinal direction is orthogonal to a lineparallel to an axis of rotation of the second stage rotary compressor,the oil feed rod having an open interior for the receipt of oil as wellas a plurality of openings formed in the exterior periphery of the oilfeed rod through which oil from the open interior of the oil feed rodcan pass into the transfer volume.
 2. The apparatus of claim 1, whereinthe oil feed rod extends from a wall that defines the transfer volumeand terminates at an end, the exterior periphery of the oil feed roddefined between the wall and the end.
 3. The apparatus of claim 2,wherein the oil feed rod includes a circular cross-sectional shape, andwherein each of the plurality of openings are symmetric.
 4. Theapparatus of claim 2, wherein the oil feed rod is in the form of ahollow tube, and wherein the plurality of openings are sized to producea spray of oil droplets.
 5. The apparatus of claim 4, wherein the oilfeed rod further comprises a second plurality of openings formed in theexterior periphery of the oil feed rod, the second plurality of openingsconfigured to discharge the oil in a non-orthogonal direction relativeto the longitudinal direction.
 6. The apparatus of claim 4, wherein theoil feed rod includes at least one opening at the end of the tube. 7.The apparatus of claim 2, wherein the oil feed rod includes anasymmetric distribution of the plurality of openings such that theplurality of openings are isolated on a portion of the exteriorperiphery.
 8. The apparatus of claim 1, wherein the openings of the oilfeed rod include a plurality of elongated slots that extend parallel tothe longitudinal direction.
 9. An apparatus comprising: a first contactcooled compressor stage that includes a first pair of compressor rotors;a second contact cooled compressor stage having a second pair ofcompressor rotors; a passage that connects an outlet of the firstcontact cooled compressor stage to an inlet of the second contact cooledcompressor stage; and an oil delivery rod having an external oildelivery surface that extends in a longitudinal direction, the oildelivery rod positioned to extend into the passage such that thelongitudinal direction is orthogonal to a line parallel to an axis ofrotation of the second pair of compressor rotors, the external oildelivery surface including a plurality of openings positioned between afirst exposed end of the oil delivery rod and a second exposed end ofthe oil delivery rod, the plurality of openings configured to spray oilinto a passing flow of working fluid produced by the first contactcooled compressor stage.
 10. The apparatus of claim 9, wherein theplurality of openings extend between an inner surface of the oildelivery rod and the external oil delivery surface.
 11. The apparatus ofclaim 10, wherein the plurality of openings are elongated slottedopenings.
 12. The apparatus of claim 10, wherein the plurality ofopenings are sized to atomize oil that is conveyed through the openings.13. The apparatus of claim 12, wherein a spray pattern formed by theplurality of openings extends around the entirety of the periphery ofthe oil delivery rod.
 14. The apparatus of claim 12, wherein theplurality of openings includes an opening formed at an end of the oildelivery rod.
 15. A method comprising: compressing a working fluid witha multi-stage contact cooled compressor; routing the compressed workingfluid from a first stage to a second stage of the multi-stage contactcooled compressor; and spraying oil out of an elongated oil rod in aninterstage region between the first stage and the second stage, theelongated oil rod elongated in a longitudinal direction that isorthogonal to a line parallel to an axis of rotation of the second stageof the multi-stage contact cooled compressor, the elongated oil rodhaving a plurality of openings formed in the elongated oil rod andarranged along the longitudinal direction such that oil is provided tothe compressed working fluid from the first stage prior to beingentrained in a compression process of the second stage.
 16. The methodof claim 15, wherein the spraying includes atomizing the oil.
 17. Themethod of claim 15, wherein spraying includes conveying the oil throughthe plurality of openings having a slot shape.
 18. The method of claim15, wherein the spraying includes isolating the spraying to one side ofthe oil rod such that an oil spray pattern is not omnidirectional. 19.The method of claim 15, which further includes spraying oil through anopening formed in an end of the elongated oil rod such that a spraypattern provided by the opening formed in the end of the elongated oilrod extends in a direction along a length of the elongated oil rod.